Makindo Medical Notes

Related Subjects: |Hypercalcaemia |Multiple Myeloma |Extramedullary Plasmacytoma |Smouldering Myeloma |MGUS |Waldenstrom Macroglobulinaemia |Oncological emergencies

Plasmacytoma is distinct from multiple myeloma due to the absence of hypercalcemia, renal insufficiency, anaemia, and multiple bone lesions. It can present as a single mass, either in the bone or soft tissue.

About

• Extramedullary Plasmacytoma: A soft tissue mass composed of clonal plasma cells, localized and often found in the head and neck region.
• Solitary Bone Plasmacytoma: Localized bone lesion without systemic involvement. Men are more commonly affected than women (2:1 ratio).

Aetiology

• Typically, a single lytic bone lesion or an isolated soft tissue mass composed of clonal plasma cells identified via biopsy.

Clinical Features

• Affects adults aged 50-80 years, with a median age of 55.
• Symptoms include localized bone pain, pathological fractures, and soft tissue masses.
• Rare presentation, either as a bone marrow lesion or an extramedullary tumour.

Differentials

• Multiple Myeloma
• Other B-cell proliferative disorders

Investigations

• Blood tests: Full blood count (FBC), U&E, and calcium levels are typically normal.
• Serum Protein Electrophoresis: Monoclonal spike present in approximately 60% of cases.
• Monoclonal protein levels: Serum protein <30g/L or Bence-Jones protein <500mg/24h.
• Bone Marrow Biopsy: Monoclonal plasma cells <10% to confirm localized disease.
• Skeletal Surveys: X-rays or CT scans show punched-out lesions and assess for other primary tumours.
• Imaging: Punched-out lesions with well-defined borders, often eroding or expanding bone cortex. Soft tissue masses are visible on imaging as well.
• Absence of CRAB (hypercalcemia, renal insufficiency, anaemia, bone lesions) criteria and no systemic involvement according to the International Myeloma Working Group (IMWG).

Management

• Radiotherapy: The primary treatment for plasmacytoma. Radiotherapy is highly effective, with local control rates of >80%, and is often given with curative intent.
• Surgery: May be considered for extramedullary plasmacytoma, particularly when located in the head, neck, or other accessible soft tissues.
• Plasmacytoma can progress to multiple myeloma in many cases, with a life expectancy of 7-10 years post-progression.